In addition to having control over which items are shown in QuickPick, you also have a lot of flexibility in controlling how they are displayed.
To move items:
Each grid page has separate view options for maximum flexibility. With these View Options you can control icon size, the grid spacing, snapping behavior, file name position and text size, and more. To show the View Options panel, use the menu item in the action menu or Page menu in the menubar.
To use the current page's view options as the default settings for new pages, and any pages set to the default settings, click on the "Use as Default" button. The "Reset" button will reset the current page's view option settings back to the previously chosen default settings. This allows you to set the view options once and share it between multiple pages via the default.